苹果浑浊汁稳定性研究进展

苹果富含苹果多酚、类黄酮、果胶、多种维生素、矿物质等营养成分。现代生活节奏不断加快,将苹果加工为营养丰富的即食苹果浑浊汁越来越受到人们青睐。分析了我国苹果产业生产现状,介绍了苹果汁分类情况和苹果浑浊汁生产过程中的主要问题。重点阐述了影响浑浊苹果汁稳定性的主要因素和改善方法,以期为改善我国苹果浑浊汁品质和稳定性提供参考,为苹果汁产业的健康快速发展提供理论借鉴。     

现代分离技术与装备在橙汁加工中的应用

现代科技的发展以及人类社会对食品安全、营养与健康要求的提升,推动了果蔬汁加工技术由传统型向现代产业型转变的进程。现代的果蔬汁加工除应用流体与流体输送、热力学（传导与热交换）、生物学（酶制剂）、制冷技术等工程原理之外,已经扩展到高效榨汁、固液分离、蒸发浓缩、蒸馏与精馏、萃取、吸附与离子交换、膜分离等物理分离技术与装备的应用方面。在橙汁加工中,不仅要求去除对橙汁风味、品质构成不利影响的橙皮精油、橙皮苷物质,同时还要求最大限度减少热敏物质及维生素C等成分的损失。讨论了采用物理分离技术与装备同其他作业单元的完美组合,限制对橙汁品质构成不利影响物质的引入,降低营养成分的损失,使得橙汁获得色、香、味俱佳品质的方法;并对备受关注的橙汁加工副产品橙皮渣废弃物转化为新资源进行综合利用,提升新的经济增长点提出了建议。     

The effect of ascorbic acid,citric acid and low pH on the extraction of green tea: How to get most out of it

Green tea seems to have a positive impact on health due to the therein-found flavanols. The amounts of these substances depend on tea preparation. In this paper, the influence of steeping time (3–7 min) and temperature (70–100 °C) on the content of the main flavanols in green tea (epicatechin EC, epicatechin gallate ECg, epigallocatechin EGC, and epigallocatechin gallate EGCg) is presented. Furthermore, additives (phosphate buffers, ascorbic acid in different amounts, and citric acid) are used to investigate the influence of pH, antioxidative, and chelating agents, simulating the addition of lemon juice or pure vitamin C.     

香蕉汁储藏过程中非酶褐变的研究

本文探讨了香蕉汁储藏中非酶褐变的原因与动力学。结果表明还原糖与氨基化合物发生的Maillard反应是造成香蕉汁储藏期间非酶褐变的主要原因。经与一级动力学和零级动力学模型拟合，推测香蕉汁储藏期间的非酶褐变符合零级动力学方程，其发生非酶褐变的活化能为80．46kJ／mol。     

苯酚—硫酸法测定仁东大蒜中的总糖

对大蒜总糖的提取条件进行优化,研究表明,6 mol/L提取剂盐酸的量为10.0 mL、加入蒸馏水15 mL、提取时间为30min沸水浴加热时为最佳提取条件。以葡萄糖为对照,采用苯酚-硫酸做为显色剂,对该法从检测波长、显色剂用量、显色时间、显色温度等方面进行最佳显色条件的研究。结果显示,最佳显色条件为精密吸取对照品溶液和供试品溶液0.2 mL,加蒸馏水至2.0 mL,加入浓度为5%苯酚1.0 mL,迅速滴加浓硫酸5.0 mL,室温25℃放置5 min后摇匀,沸水浴加热15 min,冷却至室温25℃,在最大吸收波长490 nm处测定吸光度。该方法的线性范围为5.05μg/mL~40.4μg/mL,标准溶液和试样的精密度RSD分别为1.58%和1.08%,加标回收率为95.74%~98.28%。该方法用于玉林仁东等9种不同产地的大蒜总糖含量的测定,得大蒜中总糖的含量为170.0 mg/g~220.0 mg/g。     

响应面法优化慈姑甘蔗汁复合澄清剂

以透光率为指标,利用响应面试验优化慈姑甘蔗汁的复合澄清剂配方,实验得出慈姑甘蔗汁澄清的最佳工艺条件为:瓜尔豆胶用量0.06％,明胶用量0.20％,羧甲基纤维素钠用量0.25％.用优选方案所制备的慈姑甘蔗复合饮料的透光率为89.438％,澄清效果好.     

Expression Patterns of Sugar Transporter Genes in the Allocation of Assimilates and Abiotic Stress in Lily

During the growth cycle of lilies, assimilates undergo a process of accumulation, consumption and reaccumulation in bulbs and are transported and allocated between aboveground and underground organs and tissues. The sink–source relationship changes with the allocation of assimilates, affecting the vegetative growth and morphological establishment of lilies. In this study, the carbohydrate contents in different tissues of five critical stages during lily development were measured to observe the assimilates allocation. The results showed bulbs acted as the main source to provide energy before the budding stage (S3); after the flowering stage (S4), bulbs began to accumulate assimilates as a sink organ again. During the period when the plant height was 30cm with leaf-spread (S2), leaves mainly accumulated assimilates from bulbs through the symplastic pathway, while when leaves were fully expanded, it transformed to export carbohydrates. At the S4 stage, flowers became a new active sink with assimilates influx. To further understand the allocation of assimilates, 16 genes related to sugar transport and metabolism (ST genes) were identified and categorized into different subfamilies based on the phylogenetic analysis, and their protein physicochemical properties were also predicted. Tissue-specific analysis showed that most of the genes were highly expressed in stems and petals, and it was mainly the MST (monosaccharide transporter) genes that were obviously expressed in petals during the S4 stage, suggesting that they may be associated with the accumulation of carbohydrates in flowers and thus affect flower development process. LoSWEET14 (the Sugar will eventually be exported transporters) was significantly correlated with starch in scales and with soluble sugar in leaves. Sugar transporters LoHXT6 and LoSUT1 were significantly correlated with soluble sugar and sucrose in leaves, suggesting that these genes may play key roles in the accumulation and transportation of assimilates in lilies. In addition, we analyzed the expression patterns of ST genes under different abiotic stresses, and the results showed that all genes were significantly upregulated. This study lays a solid foundation for further research on molecular mechanism of sink–source change and response to abiotic stresses in lilies.     

α-葡聚糖酶在蔗汁澄清工艺中的应用研究

使用细丽毛壳菌发酵生产的α-葡聚糖酶粗酶液在蔗汁中进行试验,试验结果表明,在混合汁中添加粗酶液,用常规的亚硫酸法工艺进行澄清处理,过滤速度与沉降速度均提高了40%,葡聚糖除去率为20%,清汁混浊度降低60%,色值降低10%。在混合汁、清汁与糖浆中添加粗酶液,葡聚糖含量分别减少20%、15%与5%。葡聚糖酶的加入对蔗糖无影响。     

野生酸枣汁乳酸菌饮料的研究

通过采用4因素3水平的正交试验,对野生酸枣汁乳酸菌饮料的最佳工艺配方进行了研究。结果表明最佳配方为混合枣汁10%、白砂糖9%、发酵乳30%、乳化稳定剂0.30%、42℃发酵4h、菌种比1∶1、接种量3%。     

热处理对鸭梨汁色泽和稳定性影响研究

研究了热处理对鲜榨鸭梨汁色泽和稳定性的影响及处理后4℃下贮藏期间鸭梨汁品质的变化。研究结果表明,不同温度和时间热处理后的鸭梨汁L值显著降低,ΔE值显著增加（p〈0.05）,透光率有不同程度的下降,一级动力学公式能很好地分析L值的变化。4℃下贮藏4周内,鸭梨汁色泽指标和稳定性指标随处理温度的变化存在不同程度的变化,表明不同热处理对鸭梨汁色泽和稳定性影响显著（p〈0.05）。